This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Primary cilia are present on most mammalian cells but their function is poorly understood in mammalian dentition. A growing number of disorders including Bardet-Biedl syndrome, Oral facial digital syndrome I, and Ellis-van Creveld syndrome have been attributed to mutations in genes that function in primary cilia or basal bodies. In addition to common pathologies such as development of renal cysts and skeletal defects, several of these disorders also have defects in tooth patterning, development or morphogenesis. Despite this evidence that primary cilia are important for the morphogenesis of the tooth, little research has been devoted to understanding the function of primary cilia in the mammalian dentition. The goal of this project is to examine the maturation of the molars in a murine model that features defective primary cilia, the Ift88orpk mutant mouse. In addition to pathologies including polydactyly, hydrocephalus and renal cysts, Ift88orpk mutant mice develop an ectopic molar. The maturation of the molars in this mouse model has not been investigated. Examination of molar morphogenesis and maturation in this mouse model will provide insight into the role primary cilia play in mammalian tooth development and how defective cilia function in these syndromes leads to changes in tooth structure.